TPR Chapter 14: The Reproductive system

scrotum

- External sac that contains the testes. - Regulates the temperature of the testes. Spermatogenesis occurs at temperature lower than body temperature. - Relaxation of the scrotum facilitates cooling of the testes. - Requires high testosterone levels.

Follicle stages of development terminology: - primodial follicle. - zona pellucida. - graafian follicle. - corona radiata. - corpus luteum.

- Granulosa cells assist in maturation of oocyte. - Location of PRIMODIAL FOLLICLE, (primary oocyte + single layer of follicle cells) - As primordial follicle develops, the granulosa cell proliferates forming several layers, and the oocyte forms the ZONE PELLUCIDA, a layer of muco-polysaccharides. - GRAAFIAN FOLLICLE: mature ovarian follicle ready to rupture and release its secondary oocyte and zona pellucida into fallopian tube. - CORONA RADIATA: The outermost, protective coat of an unfertilized egg. Directly adjacent to the zona pellucida *Its main purpose in many animals is to supply glycoprotein to the cell. - CORPUS LUTEUM: A yellow mass of cells that forms from a mature ovarian follicle after ovulation and that secretes progesterone. If fertilization of the egg occurs, the corpus luteum persists for the first few months of pregnancy

Sertoli cells (sustantecular cells).

- Located in the semineferous tubules of the testes. - Protect and secrete nutrients for developing sperm. - Secrete androgen binding protein, which maintains the levels of testosterone hormones, that enable spermatogenesis in the seminiferous tubules and sperm maturation in the epididymis. - spermatogonia are found between the sertoli cells (diploid cell). - Stimulated by FSH.

Testes

- Male primary sex organ (gonad). - Site of spermatogenesis and secretion of the male sex hormones (testosterone). - House the seminiferous tubules.

Spermatogenesis

- Production of sperm at the semineferous tubules of the testes. - Begins at puberty. - Development *Spermatogonium (2n). * Primary spermatocyte (2n; results of mitosis). * Secondary spermatocyte (1n; result of meiosis I). * Spermid (1n; result of meiosis II). * Spermatozoa (1n; spermatogenesis). - Multiplication phase end result: Spermatogonium - Growth phase end result : Primary spermatocyte - Maturation phase end result: econdary spermatocyte - Spermatogenesis end result: Spermatozoa.

Ovarian Cycle: Follicular Phase

1. Follicular phase: - Occurs from day 1- 13. - FSH from anterior pituitary stimulates growth of follicles. - Follicles grow and a Graafian follicle is produced. - Granulosa cells of the follicle secretes estrogen and inhibin. - increasing level of estrogen and inhibin inhibits FSH. - Increasing level of estrogen then stimulates LH surge. 2. Ovulation phase: - occurs on day 14. - LH stimulates the release of oocyte from ovary to pelvic cavity. - The uterine tube picks up ovulated oocyte. 3. Luteal phase: - occurs on day 15-28. - LH stimulates development of corpus luteum from ovulated follicle. - Corpus luteum secretes progesterone and estrogen. - Progesterone and estrogen prepares endometrium for possible pregnancy.

female external genitalia

1. Labia: skin fold that encloses opening: vaginal and urethral opening. - greater vestibular gland: near the back of the vestiuble. *secretes alkaline mucous on arousal. 2. Mammary glands: produce milk to nurse an infant. 3. Vagina.

Sperm structure and function

1. acrosome = fuses with ovum to allow penetration. 2. head = stores DNA. 3. mid piece = mitochondria make ATP for movement of.... 4. flagellum = pushes into female

Structures of inner mass cells.

Amnion: - Fluid filled cavity containing the developing embryo. Yolk sac: - First site of RBC synthesis in embryo. Allontosis: - Develops the embryonic gut. - Forms blood vessel of umbilical cord which transports blood between the embryo and placenta.

Arousal (male sexual act)

Arousal is dependent on the parasympathetic nervous system. Comprised of two stages. Erection: - Dilation of the arteries supplying the erectile tissues. - Arterial dilation obstructs venous outflow which creates high pressure in the erectile tissue. Lubrication: - The bulbourethral glans secretes alkaline viscous mucous and lubrication. Nitric oxide is the neurotransmitter that facilitate the parasympathetic nervous system.

Male sexual act: 3 stages.

Arousal, orgasm and resolution. Sexual act is controlled by the integrating centre in the spinal cord which response to physical stimulation from the brain

Epididymis

Bring sperm to maturity. Here, the sperm gains mitochondria and develops mitochondria.

Cleavage

Cell division without growth. Skips G1 and G2 phase. First stage of embryogeneisis. Zygote undergoes multiple rotational cleavage to generate a MORULA, a solid ball of cells.

Environmental and gene interaction of fetus. - Decreased folic acid. - Influenza. - Measles. - Open neural tube. - Hypoxia. - Alcohol consumption.

Decreased folic acid: Defect in neural tube and CNS formation. Influenza: - schizophrenia. Measles: - deafness, eye abnormality, heart defect. Open neural tube. - spina bifida. Hypoxia: - decrease in grey matter. Alcohol consumption: - fetal alcohol syndrome.

Neurulation

Development of the nervous system. - Mesodermal cells form the notochord. - Signal from the notochord causes inward folding of ectodermal cells at the neural plate. - The neural plate eventually fuse together to form the neural tube. The neural plate will develop into the neural tube which gives rise the CNS. The neural crest separate from the neural tube and form the cord's sensory neurons, eventually coming to be the PN.

Stages of labor.

Dilation of cervix, actual birth and explusion of the placenta.

Gender development during embryogenesis.

During early development, male and female fetus are indistinguishable. XX is the default sex and female genital are the default setting. In the absence of testosterone the Mullerian duct develops. Y chromosome is needed to develop internal male organs such as the testes, epididymis, seminal vesicle and vas deferen. The testes in turn produce testosterone which stimulates the Wolffian ducts to develop.

Mullerian ducts

Earlier embryonic ducts that can develop into female internal genitalia (uterine tube, uterus and vagina) in the absence of Y chromosome.

Wolffian ducts

Early embryonic ducts that can develop into male internal genitalia (epididymis, seminal vesicle and the vas defern) under the stimulation of testosterone. Y chromosome is needed to develop the testes, which produce testosterone. Testosterone stimulates Wolffian ducts formation. Testosterone must be converted to DHT for external male genital formation. THe tests also stimulate Mullerian inhibiting factor (MIF) which degenerates the Mullerian ducts.

Reproductive hormone regulation: Female - FSH. - LH. - Estrogen. - Theca cells.

FSH: - Stimulates the growth of ovarian follicles which contains maturing egg. - This enhances secretory tissues surrounding the follicle, which in turn releases increasing amount of estrogen. LH: - One the threshold level of circulating estrogen is achieved in the blood, LH surge occurs which triggers the burst of the ovarian follicle and ovulation. - The ruptured follicle develops into the corpus luteum an "endocrine gland" and begins to release progesterone. Estrogen: - regulates the uterine and ovarian cycle in reproduction. - Facilitates fusion of epiphyses in females. - Decreases estrogen results in increases LDL and osteoclast in blood (osteoporosis). Thecal cells: binding of LH to theca cells results in androstenedione production. androstenedione is connverted to estrogen by granulosa cells.

Fertilization and Sperm action.

Fertilization of secondary oocyte occurs in the uterine tube. CAPACITATED: - term for sperm that is in the cervix. ACROSMAL REACTION: - Several sperm must penetrates the corona radiata and bind to receptors on the zona pellucida. - Binding to the zona pellucida results in hydrolytic enzyme release by exocytosis. - One sperm makes contact with the cell membrane. CORTICAL REACTION: prevents polyspermy through fast block and slow block mechanism. - Fast block: depolarization of egg membrane to stop multiple fertilization. - Slow block: influx of Ca2+ due to depolarization causes zona pellucida to harden and separate from the egg surface. EGG ACTIVATION. - Secondary oocyte completes meiosis II to become an ovum. SYNGAMY: - Fusion of ovum and sperm nuclei to form a zygote.

Stages of Embryogenesis

Fertilization, cleavage, blastulation. gastrulation, organogenesis, metamorphosis, gametogenesis.

sygamy

Fusion of two haploid cells to from a zygote. Both sperm and the egg contribute equally to the genome of the zygote. The egg then contributes everything else.

Male reproductive system: hormonal regulation, GnRH, FSH, LH and inhibin.

GnRH: (gonadotropic releasing hormone), released by the hypothalamus stimulates the release on gonadtropins FSH and LH from the anterior pituitary. FSH: Targets the sertoli cells (sustentacular cells) of the testes. In turn the sertoli cells stimulates the production of sperm. LH: Stimulates the Leydig (interstitial) cells to release testosterone. Testosterone is important for adequate sperm production. Without it, sperm cells do not mature properly. Inhibin. Elevated testosterone levels stimulate the sertoli cells and granulosa cells to secrete inhibin, which inhibits FSH.

uterine cycle phases

Goal: preparation of endometrium for implantation. Menstruation phase: - occurs on day 1-5. - Low level of estrogen and progesterone level. - Results in degraded endometrium. Proliferation phase. - occurs on day 6-14. - Rising levels of esterogen. - Rebuilding of the functional layer of the endometrium. Secretory phase: - Occurs on day 15-28. - Begins after ovulation. Corpus luteum produces estrogen and progesterone. - Enrichment of blood supply and glandular secretion of lipids and protein for embryo. Both the menstrual and proliferation phase occurs before ovulation. Together they correspond to the follicular phase of the ovarian cycle. The secretory cycle = luteal phase.

If pregnancy occurs

If fertilization occurs, the developing embryo becomes implanted in the endometrium and a placenta begins to develop. The CHIRION (trophoblast and portion of placenta derived from zygote) secretes hCG which takes the role of LH in the corpus luteum.

accessory glands of male reproductive system

Main function is to make semen. seminal vesicles, prostate gland, and bulbourethral glands

Gastrulation

Migration of blastocyst cell inwards leading to multiple distinct layers called germ layers. Primary germ layers: ectoderm, mesoderm, endoderm

resolution (male sexual response)

Occurs after orgasm. Constriction of the erectile arteries. Penis becomes flaccid. Drainage of blood into dorsal vein. Controlled by the sympathetic nervous system.

Orgasm

Orgasm is controlled by the sympathetic nervous system. Includes emission and ejaculation. Emission: - movement of sperm from the vas deferen and semen from the accessory glands into the urethra by smooth muscle contractions. Ejaculation: reflexive rhythmic contraction to push semen out of the male body. Neurotransmitter: norepinephrine. in females it is mainly a series of rhythmic contraction of the pelvic floor muscles and the uterus.

Oogenesis

Ovary: Female primary sex organ. - makes ovum, estrogen and progesterone. Oogenesis: 1. Prenatal stage: oogonia --(mitosis)--> oogonia --activation---> PRIMARY OOCYTE (2N; halted at prophase 1). 2. During puberty, hormonal changes stimulates completion of the meiosis I generating SECONDARY OOCYTE (1N) and the first polar body. *fertility drug work to increases # of primary oocyte*. 3. Fertilization facilitates meiosis II, generating an OVUM (1n) and the secondary polar body. Result of OOgenesis: 1 ovum and 2 polar bodies.

seminal vesicles

Produces fluid rich in sugars (designed to feed sperm) that mixes with sperm and makes up a ~ 60 % of semen.

Female orgasm.

Results in the elevation of the CERVIX and UTERUS, and slight opening of the cervical canal and lumen of the uterus.

pathway of sperm

SEVEN-UP - Semineferous tubules. - Epididymis. - Vas deferen (ductus deferen). - Ejaculatory duct. - N(othing). - Urethra. - Penis.

sagittal plane vs transverse plane

Sagittal plane: vertical division of the body into right and left portions. transverse plane: horizontal division of the body into upper and lower portions

Male reproductive system: - Glands, secretion, function and total % of ejaculatory volume. - Seminal vesicle. - prostate gland. - bulbourethral gland. - testes.

Seminal vesicle: - Secrete fluid rich in fructose. - Nourishment of sperm. Sugar source of mitochondria. - ~ 60% of ejaculatory volume (sperm + fluid = semen). Prostate gland: - Secrete fructose and coagulants. - Allows sperm to coagulate after ejaculation. - ~ 35% Bulbourethral gland: - Secretes thick alkaline mucous. - Lubricates the urethral. - Neutralizes acid in urethra and vagina. - activated by arousal. - ~ 4 %. Testes: - Secretes sperm. - ~1 % of total ejaculatory volume.

semineferous tubules

Site of spermatogenesis in the testes. The walls of the semineferous tubules are called sustantecular cells.

Differentiation vs determined.

Step 1. Determination: - Cell is committed to a particular fate, but has not undergone physical changes to become that cell type. - Result of a asymmetric segregation of cytoplasmic determinant. - occurs in totipotent embryonic stem cell. - irreversible Step 2: Differentiation.: - Cell undergoes physical changes and becomes specialize, in order to perform a specific function. - result of differential gene expression.

Homologous reproductive structures between male and females.

Testes and ovary: - gamate and hormone production. Penis and clitoris: - erectile tissue. arousal during intercourse. Bulbourethral and greater vestibular glan: - Lubrication during coitus. Scrotum and labia majora: - external skin folds.

What occurs if the testosterone levels are abnormally elevated in an adolescence.

Testosterone levels are normally low before puberty. If it is elevated, the child will be unusually tall, but early fusion of the epiphyses will result in shorter adult height than expected.

testosterone, DHT, androstenedione

Testosterone: - Differentiation of seminal vesicle, vas deferen and epididymis. - Spermatogenesis. - Pubertal growth spurt. - Increase in muscle mass, bone density and RBC production. - Voice deepening. - Closure of epiphyseal plate of bone. - Libido. DIhydroxyltestosterone (DHT): - Differentiation of external genital (penis and scrotum) and prostate. - Growth of prostate. - Activity of sebaceous gland. - Male hair pattern and baldness.

Menstral cycle

The hormone-controlled cycle in the human female, lasting about a month, in which an egg matures and is released from the ovary and the uterus prepares to receive it. 2 cycles: ovarian and uterine cycle. Hormone regulation: - Hypothalamus release GnRH which acts on the anterior pituitary. - Anterior pituitary releases FSH and LH which acts on the ovary. - The ovary releases estrogen and progesterone which acts on the uterus. Feedback inhibition. - High levels of estrogen inhibits hypothalamus and anterior pituitary. - High levels of estrogen and progesterone strongly inhibits the LH and FHS.

birth control pill mechanism

The hormones in the pill, progestin (which mimics progesterone) and estrogen, decrease the release of GnRH, and therefore the release of FSH and LH. This restricts the follicles from growing, and by extension, an egg from growing and releasing from the ovary. Essentially, these synthetic hormones trick the ovary into thinking that it's already released an egg. The endometrium still builds in the uterus and is released. This is why a period while on the pill is usually lighter and shorter. the corpus luteum can't grow unless the ovary has released an egg. The progestin may also make it harder for sperm to enter the fallopian tube by making the vaginal mucus thicker.

Testosterone

The primary androgen (male sex steroid). Steroid hormone produced and secreted by the interstitial cells of the testes. It triggers the development of secondary male sex characteristics during puberty. Increases number of RBCs by stimulating the kidney to produce EPO. Too much leads to baldness and prostate cancer.

Blastulation

The process by which a morula develops into a blastocyte, which contains the trophoblast, inner mass cells and a fluid-filled cavity called a blastocoel. Firs differentiation occurs here. TROPHOBLAST: - the peripheral cells of the blastocyst, which attach the zygote (fertilized ovum) to the uterine wall - - become the chirion and later the placentathat nourish and protect the developing organism. - Secretes hCG. - INNER MASS CELL: also known as the embryoblast or pluriblast, is a group of cells in a fertilized egg that develops into an embryo, the amnion sac and umbilical cord. The blastocoel: - A fluid filled cavity that permits cell migration during gastrulation. - It prevents the animal cells, destined to become ectoderm, from premature induction by the underlying vegetal cells into mesoderm.

Implantation

The process by which the zygote attaches to the uterine wall. APPOSITION: - Attachment of developing blastocyst into the endometrium. ADHESION: - THe blastocyte sinks into the endometrium and is surrounded by it. - occurs after the trophoblast secrete protease that lyse some endometrium cells. PLACENTAL VILLI: - Chorionic villi that sprout from the chorion to provide maximal contact area with maternal blood. Branches of the umbilical arteries carry embryonic blood to the villi.

totipotent, pluripotent, multipotent

Totipotent cells are cells that can differentiate into any embryonic cell. - Example: Zygote. Pluripotent cells are cells that are capable of developing into most, but not all, of the body's cell types. - Example: Found only in inner mass cells. Multpotent cells (adult stem cells) are cells that only differenciate into related cells. - Example: Mesenchymal cells can differentiate into bone, cartilage or connective tissue.

ductus arteriosus

a blood vessel in a fetus that bypasses pulmonary circulation by connecting the pulmonary artery directly to the ascending aorta.

Labor contraction is the result of ....

a positive feed back reflex. The increase pressure in the cervix crossses a threshold that causes the posterior pituitary to secrete oxytocin. Oxytocin causes the uterine contraction to increase in intensity, creating greater pressure on the cervix that stimulates more oxytocin release.

fetal stage of development

begins at the end of the 8th week. Week 12: visible baby gender. Week 16: baby's muscle contractions can be felt by mum. Week 24: eyelids unfuse, baby responds to external stimuli. Week 28: testes descend. Week 33: surfactant is formed. Week 38: full term birth. First trimester: week 1-13. Second trimester: week 14- 26. Third trimester: week 26-40.

foramen ovale

connects the two atria in the fetal heart. bypass the lungs.

ductus venosus

connects the umbilical vein to the inferior vena cava, bypassing the liver

germ layers (list)

ectoderm, mesoderm, endoderm

Anterior and posterior

front and back

internal female reproductive organs

ovaries, fallopian tubes (oviducts, uterine tubes), uterus, and vagina. Accessory glands: - Cervix: opening to the uterus. Only opened during ovulation. When closed, it is surround by thick, sticky acidic mucus. - Uterus: site of developing embryo. Consists of myometrium and endometrium. - Endometrium: Inner lining of the uterus, that nourishes developing embryo. - Myometrium: smooth muscle wall of the uterus. Unique in that it retains its ability to divide. - Fallopian tubes: connects uterus to ovaries. contains cilla to sweep egg towards the uterus. Site of fertilization and tubal ligation.

primordial follicle

primary oocyte + single layer of follicle cells

Greater vestibular (Bartholin's) glands

produce mucous during sexual arousal to provide lubrication. They are homologous to the bulbourethral gland.

Interstitial cells of Leydig

secrete testosterone and other male sex hormones (androgens). Stimulated by LH.

vas deferens (ductus deferens)

tube that carries sperm from the epididymis to the urethra. Pathway: vas deferen --> inguinal canal --> pelvic canal --> joints the duct of seminal vesicle to form the ejaculatory canal ---> urethra. Site of vasectomy. location: posterior of the testes.

Stem cells

undifferentiated cells that have the ability to become specialized cell types and reproduce to make more stem cells. Found in the blastocyst ( embryonic stem cells) and tissue.

Analogus reproductive structures between male and females.

vas deferen and uterine tube.